Adults are large, aquatic salamander with bushy red gills, well developed limbs, and a large paddle-like tail. Dorsal coloration varies from grayish to dark brown with irregular dark blotches and the underbelly is lighter in coloration. Most adult Mudpuppies grow to around 1-1.5 ft (300-400 mm) in length.

Females lay eggs in large clumps (around 50-100 eggs) attached to the underside of submerged objects such as rocks and logs. Larval Mudpuppies are yellow to light brown with dark dorsal stripes that fade with age.

The Hellbender (Cryptbranchus alleganiensis) is similar in form and size to the Mudpuppy, but grows roughly twice as large, has loose folds of skin laterally, and lacks external gills. In Indiana, these two salamanders were likely found together throughout the Ohio River and its tributaries at one time, but now the Blue River is the only place in the state where the Hellbender occurs.

Ecology and Conservation

Mudpuppies are found in a wide variety of permanent, aquatic habitats. They occur in clean-flowing rocky streams and large, turbid rivers as well as man-made reservoirs and into the deeper portions of Lake Michigan. They do best when ample cover is present such as rock slabs, logs, and undercut banks. Mudpuppies are active year round and have been captured by ice fisherman in deep lakes during the middle of winter. They are apparently most active from late fall into spring. Mudpuppies feed on a variety of aquatic organisms ranging from fish and amphibians to small invertebrates. In many populations, they appear to prey heavily on crayfish.

Breeding season for this species varies regionally, but in general this species breeds during the fall or winter and females deposit eggs during early summer (May-July). Mudpuppies require some sort of submerged structure on which to attach their eggs. In many cases, Mudpuppies will attach their eggs to the underside of large flat rocks and logs. Females remain with the eggs until after hatching in order to protect the young against fish and invertebrates that would otherwise prey on the eggs. After laying eggs, the female will remain with her nest and guard the eggs until shortly after hatching.

Although considered a species of Special Concern in Indiana, relatively little is known about Mudpuppy populations in the state. Due to the secretive nature of this species and the difficulty in sampling for them, their population ecology has been understudied. If trends in other large aquatic salamanders (primarily Hellbenders) are any indication of what is happening in this species, then populations have likely declined. Yet due to their much broader habitat preferences, it is clear that Mudpuppies have not experienced the same level of precipitous declines as have Hellbenders.

Distribution

Mudpuppies are found throughout the Great Lakes and Upper Mississippi River drainages from Louisiana and Tennessee into Canada. Scattered populations occur as far northwest as North Dakota and as far northeast as Maine.

This large, adaptable salamander is found throughout the state, but records are relatively few and scattered. Many records come from lakes and rivers where fisherman occasionally catch Mudpuppies on trot lines. Mudpuppies have been documented from many of the large rivers and lakes in Indiana and were once likely found throughout Indiana's large rivers and streams. Extensive survey work has not been done to determine the health or extent of populations in Indiana. Mussel surveys in the state have been extensive and have documented the occurrence of the Salamander Mussel (Simpsonaias ambigua) at numerous sites where there are no published records for Mudpuppies. Since the Mudpuppy is the only known host for the larval stage of this mussel, these records were included in the distribution map.

Taxonomy

Some scientists recognize multiple subspecies of the Mudpuppy (Necturus maculosus). Indiana is home to the Common Mudpuppy (N. m. maculosus). These salamanders are members of the family Proteidae, which is known from only a handful of species in the eastern United States and one species in Europe.